Protocol for wireless networks

ABSTRACT

A wireless transmission method includes providing a commanding node and a plurality of sub-networks. Each of the sub-networks includes at least one responding node. Time slots are assigned to the sub-networks such that time slots assigned to each sub-network are interleaved in time with time slots assigned to at least one other sub-network. Within each time slot, at least one acknowledgement packet is transmitted from the at least one responding node before a command packet is sent from the commanding node within the time slot. Each at least one acknowledgement packet indicates whether or not a most recent command packet from the commanding node was correctly received by the responding node.

BACKGROUND

1. Field of the Invention

The present invention relates to wireless networks, and, moreparticularly, to protocols for wireless networks.

2. Description of the Related Art

Typically, automotive body domain applications such as seat control,window lift, mirror adjustment, and light control are distributed overthe entire car and are interconnected via field bus communicationsystems. Current architectures have grown fast over the last decades asmore and more convenience functions are introduced to the automotiveindustry.

The current architectures are hierarchical architectures in whichseveral electronic control units (ECUs) are located near the body domainapplications such as the seat ECU under the seat, the door ECU withinthe door, the ECU for rear light control in the trunk of the car, etc.All these ECUs are interconnected over field bus systems such as the“controller area network” (CAN) field bus, and these ECUs form the firsthierarchy of the system. This field bus of the first hierarchy can alsobe regarded as the backbone network of the body domain.

The ECUs usually consist of a microcontroller and so-called peripheraldrivers such as semiconductor switches, relays, signal amplifiers, etc.From the ECUs, several point-to-point wires connect to the peripheralsof the applications like the motors (window, lift, seat adjustment),pushbutton panels, heating elements, sensors, etc. The number of theseperipherals is constantly increasing for each application. For example,fifteen years ago a comfort seat had only three motors to move the seatforward and backward, to adjust the backrest, and to adjust the height.However, current seats may have about fifteen motors for additionalfunctions such as air ventilation, massage functions, etc.

In order to connect the peripherals, a large number of cables may benecessary, which increases the complexity of the cable harness,increases the weight of the car, and increases the costs of the car. Theincrease in the number of cables may also lead to reliability problemsin areas where the cable harness is mounted on moveable parts such asthe side mirror, doors, seat, etc. Hence, in known architectures asecond hierarchy order in the form of a so-called “subsystem” may beprovided. Subsystems may have their own wired communication networkwhich is usually a low cost communication system such as a localinterconnect network (LIN). In contrast to the backbone, these networksare usually master-slave systems and not multimaster systems. The ECUthat has access to the backbone is usually the master and theperipherals are the slaves. The ECU is also the gateway between thebackbone and the subsystem.

The state-of-the-art of automotive electronics is progressing rapidlyand it is projected that electronics alone will make up forty percent ofthe total cost of future cars. All these electronic units in the vehicleare connected through different bus systems depending on the applicationrequirements. Typically, a hierarchical body domain automotive network100 (FIG. 1) consists of several sub-networks, such as sub-networks 112,114, connected together to form a larger network. The sub-networkstechnology being used is, for instance, a Local Interconnect Network(LIN). Each sub-network consists of a gateway node or ECU 116 and somesensor/actuator nodes 118. Network 100 may include a wired backbone 120compatible with a Controller Area Network (CAN), FlexRay, Ethernet, etc.Network 100 may also include a body computer 124 and wired communicationlinks 122 compatible with a CAN, Local Interconnect Network (LIN),FlexRay, Ethernet, etc.

ECUs 116 may be interconnected with each other over wired backbone fieldbus systems 120. Peripherals 118 may be directly connected to ECUs 116.Peripherals 118 may include tiny electronics and may communicate overanother field bus with the main ECU. Thus, ECUs 116 may function in sucharchitecture as gateways which communicate on one end with networkbackbone 120 and on the other end with the local sub-networks. Thesub-networks may be organized in master-slave relationships in which theECU is the master for the distributed tiny electronics in peripherals118.

A problem associated with the architecture of FIG. 1 is that is that ithas poor reliability. For example, if one of the ECUs fails, then theentire associated subsystem is no longer able to operate. Anotherproblem is that there may be long time delays for end-to-endcommunication as gateways become bottlenecks. Yet another problem isthat modularity and scalability are limited by the underlyingsub-network systems.

Although implementing at least some of the architecture of FIG. 1wirelessly has been considered, wireless communication is unpredictableand hence raises questions about the responsiveness of such a system ascompared to wired networks. Another challenge is in operating theactuators in a given priority order.

What is neither disclosed nor suggested in the art are protocols thatmay avoid the above-mentioned problems and provide more robust networkperformance.

SUMMARY OF THE INVENTION

The present invention provides novel protocols for controlling actuatorsin wireless networks. The present invention may be applicable forautomotive networks as well as for other applications. For example, theprinciples of the present invention may be applied to industrialnetworks, cargo, airplanes, ships, etc.

The invention comprises, in one form thereof, a wireless transmissionmethod including providing a commanding node and a plurality ofsub-networks. Each of the sub-networks includes at least one respondingnode. Time slots are assigned to the sub-networks such that time slotsassigned to each sub-network are interleaved in time with time slotsassigned to at least one other sub-network. Within each time slot, atleast one acknowledgement packet is transmitted from the at least oneresponding node before a command packet is sent from the commanding nodewithin the time slot. Each at least one acknowledgement packet indicateswhether or not a most recent command packet from the commanding node wascorrectly received by the responding node.

The invention comprises, in another form thereof, a wirelesstransmission method including providing a commanding node and aplurality of sub-networks. Each of the sub-networks includes at leastone responding node. Time slots are assigned to the sub-networks suchthat time slots assigned to each sub-network are interleaved in timewith time slots assigned to at least one other sub-network. Within eachtime slot, a command packet is transmitted from the commanding node andat least one acknowledgement packet is transmitted from the at least oneresponding node. The command packet includes a respective selection bitfor each of the responding nodes in the sub-network that is assigned toa current time slot. Each selection bit indicates whether the respectiveresponding node is to operate. The command packet also includes at leastone direction bit. Each direction bit corresponds to a respectiveresponding node in the sub-network that is assigned to a current timeslot. Each direction bit indicates a mode of operation of the respectiveresponding node.

The invention comprises, in yet another form thereof, a wirelesstransmission method including providing a commanding node and aplurality of sub-networks. Each of the sub-networks includes at leastone responding node. One of a plurality of priority levels is assignedto each of the sub-networks. Time slots are assigned to the sub-networkssuch that time slots assigned to at least one sub-network areinterleaved in time with time slots assigned to at least one othersub-network of a same priority level. Within each time slot, a commandpacket is transmitted from the commanding node and at least oneacknowledgement packet is transmitted from the at least one respondingnode. The command packet includes a respective selection bit for each ofthe responding nodes in the sub-network that is assigned to a currenttime slot and is of the same priority level. Each selection bitindicates whether the respective responding node is to operate.

Advantages of the present invention include simpler implementation,modular development, superior composability, and flexibility.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features and objects of this invention,and the manner of attaining them, will become more apparent and theinvention itself will be better understood by reference to the followingdescription of an embodiment of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1 is a block diagram of a wired hierarchical body domain automotivenetwork architecture of the prior art.

FIG. 2 a is a schematic diagram of a prior art automotive body domainarchitecture.

FIG. 2 b is a schematic diagram of one embodiment of an automotive bodydomain architecture that may be used in conjunction with at least oneembodiment of a protocol of the present invention.

FIG. 3 is a block diagram of one embodiment of a network architectureincluding a wireless communication system that may be used inconjunction with at least one embodiment of a protocol of the presentinvention.

FIG. 4 a is a diagram of time-slot assignments for sub-networks in whichall sub-network time slots are accommodated on one channel, inaccordance with one embodiment of the invention.

FIG. 4 b is a diagram of time-slot assignments for sub-networksincluding optimal assignment of sub-network time slots on differentfrequency channels, in accordance with another embodiment of theinvention.

FIG. 5 is a timing diagram of one embodiment of packet formats withselection and direction bits according to one embodiment of the presentinvention.

FIG. 6 is a timing diagram of one embodiment of packet formats with nodeIDs and direction bits according to one embodiment of the presentinvention.

FIG. 7 a is a diagram of a priority order of nodes of a priority listaccording to one embodiment of the invention.

FIG. 7 b is a diagram of mutually exclusive priority lists according toone embodiment of the invention.

FIG. 8 is one embodiment of an ID translation table that may bemaintained at every node according to the invention.

FIG. 9 a is a timing diagram of a data-Ack scheme with successiveretransmissions according to one embodiment of the invention.

FIG. 9 b is a timing diagram of a data-Ack scheme with distributedretransmissions according to one embodiment of the invention.

FIG. 10 is a timing diagram of an Ack-data protocol according to yetanother embodiment of the invention.

Corresponding reference characters indicate corresponding partsthroughout the several views. Although the drawings representembodiments of the present invention, the drawings are not necessarilyto scale and certain features may be exaggerated in order to betterillustrate and explain the present invention. Although theexemplification set out herein illustrates embodiments of the invention,in several forms, the embodiments disclosed below are not intended to beexhaustive or to be construed as limiting the scope of the invention tothe precise forms disclosed.

DETAILED DESCRIPTION

The embodiments hereinafter disclosed are not intended to be exhaustiveor limit the invention to the precise forms disclosed in the followingdescription. Rather the embodiments are chosen and described so thatothers skilled in the art may utilize its teachings.

As described above with reference to FIG. 1, a wired automotive networkmay include several sub-networks connected together using a backbonenetwork of ECUs and gateways. As shown in FIG. 2 a, often severalactuators are part of one sub-network and are controlled by a singleECU. The ECU may perform the command translation and send theappropriate signals to the desired actuators in a pre-defined order. Theorder may be decided according to the functional requirements. Due topractical limitations such as power control, only a set of actuators maybe able to function at the same time.

FIG. 2 a illustrates a known automotive body domain architecture 500including central ECUs 502, 504 of a door module 506 and a seat module508, respectively. ECUs 502, 504 are interconnected by a body CAN 510.Dedicated wires run to the various actuators, such as pushbuttons 512and DC engines (i.e., motors) 514 with Hall sensors. There are fourwires connected to each motor 514. Specifically, two wires are providedin a power cable 516 for powering the motor, and two wires are providedin a communication cable 518 for connection to the Hall sensor tomeasure the revolution of motor 514. Motors 514 are provided in bothsteering elements 520, 522 and in seat elements 524, 526, 528. Heaters530 are provided in steering element 520 and in seat elements 524, 526.For each of cables 516, 518 there are at least two connectors, i.e., oneconnector for connection to the ECU and another connector for connectionto the motor/heater.

An alternative wireless architecture and seat sub-network of lower costand complexity is described in a U.S. patent application filed even dateherewith, entitled “Architecture for Automotive Electrical BodySystems”, having inventors Thomas Hogenmueller and Vivek Jain, which ishereby incorporated by reference herein in its entirety.

FIG. 2 b illustrates a wDPM-based automotive body domain architecture550 that may be used in conjunction with the present invention includingdecentralized wDPMs 552 _(a-j) instead of intermediary centralized ECUsin a door module 556 and a seat module 558. The only wiring needed istwo power cables 566, 568. Each wDPM 552 is associated with thepushbuttons 562, a motor 564 or a heater 580. Each motor 564 may have aHall sensor to measure the revolution of motor 564 and to communicatethe motor position to the associated wDPM 552 _(a-j) Motors 564 areprovided in both steering elements 570, 572 and in seat elements 574,576, 578. Heaters 580 are provided in steering element 570 and in seatelements 574, 576.

The commanding or supervising node wDPM 552 _(s) associated withpushbuttons 562 may communicate with the responding nodes wDPMs 552_(a-j) associated with seat module 558. In response to inputs from auser interface, such as a user manually pressing at least one ofpushbuttons 562, the wDPM 552 _(s) associated with pushbuttons 562 maywirelessly transmit a command signal to at least one of the wDPMs 552_(a-j) associated with seat module 558. The command signal may instructthe receiving wDPM 552 _(a-j) to actuate its associated motor 564 orapply power to, or take power from, its associated heater 580.

Each of wDPMs 552 _(a-j) associated with seat module 558 may becontrolled by commanding node wDPM 552 _(s) associated with pushbuttons562. Within such a scheme, the methods of the present invention mayimprove the responsiveness of the actuator such that the commandexecutes or starts executing within the given delay. The methods of thepresent invention may advantageously make it more likely that theoperations of higher priority actuators are over before the next groupof actuators can operate. Issues similar to those described above mayalso arise in connection with industrial networks.

Referring now to FIG. 3, there is shown an automotive network 200 of thepresent invention which may circumvent the problems of the prior art byusing wireless communication, and which may be used in conjunction withat least one wireless protocol of the present invention. Network 200includes sub-networks 211-215 which may each represent a different classof peripherals 218. For example, sub-networks 211-215 may be clusters ofpushbutton panels, lights, sensors, small electric motors, and actuatorcomponents, respectively. There may be some overlap betweensub-networks. For example, the small electric motor sub-network 214 maybe a subset of the larger actuator component sub-network 215, as shownin FIG. 3.

Wireless gateway ECUs 216 may communicate wirelessly, such as via radiofrequency communication, with wireless sensor/actuator nodes 218 withinthe sub-network of each gateway ECU 216. A body computer 224 may be indirect wireless communication with peripherals 218 in sub-networks211-215, and may communicate via the ECUs 216 with peripherals 218 thathave the ECU 216 in their sub-network.

In at least one embodiment of the invention, only one wirelesscommunication system may be used for the entire body domain. As isevident from FIG. 3, ECUs 216 may be largely eliminated. In otherembodiments, ECUs may be completely eliminated. In the absence of ECUs,the actuator, sensors, and pushbutton panels may have very smallelectronics with a wireless communication interface (e.g., a wirelessdistributed peripheral module (wDPM)). In at least one embodiment of theinvention, only a single communication interface is used for the bodydomain, replacing centrally-organized ECUs with non-centralized wDPMs,and use of the new communication pattern in which peripherals maycommunicate directly instead of using an ECU as an intermediary.

In order to provide a framework for protocols of the present invention,a generic wireless controller area network (sub-network level) may bedefined with a commanding node and N number of actuators with thefollowing five conditions. First, each actuator has a priority p_(i),where iε[1, N] and at a given time only n actuators can operate. Second,each node is equipped with a radio module and hence the mode ofcommunication between all nodes in the system is wireless. Third, thecommands issued by the commanding node fall into two categories: Memorycommands were each actuator needs to adjust itself to a pre-definedposition; and Non-memory commands which include general and diagnosticcommands. Fourth, the commanding station does not know how much time isneeded by the nodes to complete the desired action. Fifth, there are fewmemory commands wherein the desired actuators are set in pre-definedpositions. The memory positions are stored by the respective nodes andnot by the commanding stations as in current systems. This implies thatall actuator nodes know the position they have to reach for a givenmemory function. The position can be a function of steps, motorrotations, etc.

The framework for protocols of the present invention may also define thefollowing two conditions for the overall network. First, the vehicle canhave M such sub-networks in the vicinity using the same radio modulesand frequency spectrum. Second, there is a maximum time T bounding thesub-network responsiveness, i.e., the time delay between the time acommand is issued and the time when at least one operation is started is≧T, for each of these sub-networks.

The overall system requirements on the network level need to besatisfied by the protocol of the invention. Consider a time scale inwhich each sub-network is assigned a time slot as shown in FIG. 4 a. Itmay be assumed that each of these sub-networks requires t_(j) time tofinish the task, where jε[1, M]. Then, they all fit on the same timescale (or same frequency channel) while satisfying the systemrequirements, if and only if,

$\begin{matrix}{{\sum\limits_{j = 1}^{M}t_{j}} \leq {T.}} & (1)\end{matrix}$

Otherwise, more channels may be required and the time slots may bedistributed on different channels as shown in FIG. 4 b. However, it maybe most efficient to use only the minimal number of channels. Theproblem can be modeled as a 0-1 knapsack problem:

$\begin{matrix}{{{maximize}{\sum\limits_{j = 1}^{M}x_{j}}}{{{{subject}\mspace{14mu} {to}\mspace{14mu} {\sum\limits_{j = 1}^{M}{t_{j}x_{j}}}} \leq T},{x_{j} = {{0\mspace{20mu} {or}\mspace{14mu} 1\mspace{14mu} {and}\mspace{14mu} j} \in \lbrack {1,M} \rbrack}}}} & (2)\end{matrix}$

Further, if the sub-networks also have priorities P_(j), where jε[1, M]then, (2) modifies as:

$\begin{matrix}{{{maximize}{\sum\limits_{j = 1}^{M}{P_{j\;}x_{j}}}}{{{{subject}\mspace{20mu} {to}{\sum\limits_{j = 1}^{M}{t_{j}x_{j}}}} \leq T},{x_{j} = {{0\mspace{14mu} {or}\mspace{14mu} 1\mspace{14mu} {and}\mspace{14mu} j} \in \lbrack {1,M} \rbrack}}}} & (3)\end{matrix}$

The above problem by itself is nondeterministic polynomial-time hard (NPhard), but can be solved by using a Greedy approximation algorithmiteratively until all sub-networks are assigned to a time slot. This maybe achieved by sorting the sub-networks according to x_(j) or P_(j)x_(j)(depending on the case) and then putting the highest ones first on agiven channel satisfying the condition that their aggregated time isless than T. The process may be repeated until all sub-networks areaccommodated as shown in FIG. 4 b.

The invention may solve sub-network issues on a channel-by-channelbasis. There may be three types of packets in the sub-network: memory,non-memory and Ack packets as shown in FIG. 5. The protocol header foreach packet may include some of the following: message identification(ID), car ID, sub-network ID, node ID, and so on. The Ack packet mayinclude one or more bits stating whether the operation by the actuatoris over or not. An absence of an Ack packet may be an implicit negativeacknowledgment while its presence may be an explicit acknowledgement.The data packets, on the other hand, along with the protocol header alsomay include: a bit identifying the data packet as a memory/non-memorydata packet; the number of nodes in the sub-network; and/or the nodeselection bits. Bits for the actuators that should start operating maybe set to “1”.

The above information may be followed by the memory position/number bitsfor the memory data packets. In non-memory packets, selection bits maybe followed by the direction bits which inform the selected actuators toperform respective action. As an example, if an actuator is a motor,then the direction bit controls the direction of rotation as clockwiseor counterclockwise. If an actuator is a heater, then the direction bitcontrols the state as ON or OFF. The mapping of the nodes in thesub-network to the selection and direction bit positions may be doneduring the initial set-up phase. So, every node may know which bitposition or positions corresponds to that node (i.e., to itself) in thememory/non-memory packets.

An alternate packet format can also include addresses of the nodesexplicitly if the total number of nodes (n) that can operatesimultaneously is not greater than the number of node addresses that canbe accommodated within a packet. In the example shown in FIG. 6, thenumber of node addresses that may included in a packet is two (n=2). Inthis case, the memory packet has an additional field for identifyingmemory position/number as compared to the non-memory packet.

Each commanding/supervising node 552 _(s) may maintain a priority listwith nodes in a priority order, an example of which is shown in FIG. 7 a(552 _(a), 552 _(c), 552 _(b), 552 _(d), 552 _(h), 552 _(i), 552 _(j),552 _(e), 552 _(f), 552 _(g)). Considering that at a given time only nnodes can operate, the commanding station 552 _(s) while sending thedata packet may set a maximum of n selection bits depending on thepriority order. Commanding station 552 _(s) may also set the respectivedirection bits accordingly. Once commanding node 552 _(s) hastransmitted the packet, commanding node 552 _(s) may wait for the Acksin the next slot. If commanding node 552 _(s) does not receive an Ackfrom a node whose bit was set, then commanding node 552 _(s) may retainthe set bit for that node in the packet. However, If commanding node 552_(s) does receive an Ack, then, depending on whether the actuator isstill operating (denoted by the status bit), commanding node 552 _(s)may either clear its selection bit or retain it for the next packet.Once commanding node 552 _(s) has waited for the n Ack slots, commandingnode 552 _(s) may send the next packet. If at least one node is finishedoperating, then commanding node 552 _(s) may pick the next node from thepriority list.

Under certain conditions, it may not be possible for a low priority nodeto start operation until the higher priority nodes have completed theiroperation. In such cases, the commanding node may maintain mutuallyexclusive node priority lists as shown in FIG. 7 b. That is, eachcommand packet may identify one of the priority lists to which thecommand packet is addressed. In this case, the nodes in a child list maystart their operation only once the nodes in the parent list havefinished their operation. Thus, responding nodes of a same prioritylevel complete operation before the command packets are sent to theresponding nodes of lower priority levels. Commanding station 552 _(s)may initiate and complete the desired operation on a list-by-list basis.In the embodiment of FIG. 7 b, the selection bit of node e may be set to“1” only after all nodes in the parent list (a, c, b and d) havecompleted their operation. Depending on the complexity, the Memory andNon-memory packets can have an additional field for a list number. Then,the selection and direction bits may correspond to the nodes in thatlist only. The tradeoff may be a reduction in the packet length at theexpense of the added complexity that the node now should know in whichlists they lie. This information can be exchanged during the initialsetup phase.

An actuator can be controlled by several commanding nodes. Hence, eachnode may maintain a list of commanding nodes, their corresponding listnumber and its virtual node ID in that corresponding sub-network asillustrated in FIG. 8. This list maybe made during the initial setupphase. In the table, “X” denotes the state as “ON/OFF” or motorposition, etc. depending on the actuator/sensor.

In each time slot the commanding nodes of the respective sub-networksmay send the command and may seek a response from the node in order toascertain the status of the command. Considering that the channel iswireless and there might be noise on the channel, multiple suchretransmissions may be performed in order to increase the reliabilityand responsiveness of the command. Thus, the sub-network time slot(t_(j)) may include the retransmissions also. Then, on the time scale,the overall sub-network time slot can be broken into (re)transmissionslots in the following two ways as illustrated in FIGS. 9 a and 9 b. Thesuccessive retransmission scheme of FIG. 9 a may include assigning eachsub-network to consecutive time slots. The distributed retransmissionscheme of FIG. 9 b, however, may include assigning time slots to thesub-networks such that time slots assigned to each sub-network areinterleaved in time with time slots assigned to at least one othersub-network. The successive retransmissions scheme (FIG. 9 a) may bemost commonly used. However, the distributed retransmission scheme (FIG.9 b) has an advantage that if the channel is noisy for long timedurations then the distributed retransmission scheme has a betterresponse time as compared to the successive retransmissions scheme. Themain reason for this is that long noise/fading time durations can resultin loss of the main packet and its retransmissions as well.

In the distributed retransmissions scheme, the commanding node maytransmit the data packet and wait for an Ack. The first Ack slot may beoccupied by the highest priority node that has its selection bit “ON”,and so on. If the commanding node receives the Ack with a status beingthat the operation of the node is completed, then, for the next slot thecommanding node may select the next node in the priority order foroperation. Otherwise, the original node may continue its operation untilcompletion.

According to another embodiment of the invention, performance of thedistributed retransmissions data-Ack scheme of FIG. 9 b may be furtherimproved by interchanging or switching the positions of the packet andAck slots as shown in the Ack-data protocol of FIG. 10. An advantagewith the scheme of FIG. 10 is that before sending the commanding packet,the commanding station not only knows whether its last packet wasreceived by the respective nodes but also knows the status of theaction, i.e., the commanding station now knows whether to continuesending the same message or whether to send the next message. Therefore,by listening to Ack+Status before sending the packet, the present schememay save at least one transmission per every new packet as compared tothe data-Ack scheme. In the data-Ack scheme, after receiving the Ackwith status, the commanding node will transmit the next packet in thenext slot (and hence wastes the present slot). On the other hand, if thepacket was not successfully received by the intended nodes, then in bothschemes the present slot is wasted.

As advances in wireless communication technology enable seamlesscommunication on different frequencies (e.g., frequency multiplexing),completely new communication schemes can be applied, some of whichschemes may be described in a U.S. patent application filed even dateherewith, entitled “Dynamic Function Slot Assignment in Intra-VehicularWireless Networks”, having inventors Thomas Hogenmueller and Vivek Jain,which is hereby incorporated by reference herein in its entirety.

In one embodiment, a wireless protocol for an automotive electrical bodysystem may be provided. In a first operation, at least one bodycomponent is provided in a vehicle, such as a car, boat, plane, train,etc. The body component may be anything physical device that may beactuated, heated, or, more generally, caused to undergo any type oftransformation. In specific embodiments, the body component is a carseat or a steering wheel. The transformation may be, for example,mechanical, electrical, chemical, or a combination of the above.

In a next operation, a plurality of electrical assemblies are coupled tothe at least one body component. Each of the assemblies includes aheating element, a motor, or a switch. In the case of a heating element,the heating element may heat the component, such as the steering wheelor car seat. It is also possible that the heating element may heat somesubstance in the component, such as to initiate a chemical reaction. Inthe case of a switch, the switch may turn on or turn off a light. In thecase of a motor, the power may be applied to the motor to cause themotor to move some component, or at least some part of the component.For example, the motor may move a steering wheel closer to or fartheraway from a driver, or may raise or lower the base of the steeringwheel. In the case of a car seat, the motor may raise or lower the baseof the car seat; move the base of the car seat forward or backward;rotate the back of the car seat in clockwise or counterclockwisedirections; lower or raise the head rest; control air ventilation, orcontrol a massage function. In another embodiment, the motor may raiseor lower a car door window.

In another operation, a wireless communication module may be connectedto the heater or motor. The wireless communication module may receiveexternal wireless signals, such as from another wireless communicationmodule that is connected to a user interface. The user interface mayinclude pushbuttons or switches, and may be installed on a door of thecar. For instance, the user may want to apply heat to the steering wheelor seat, or may want to adjust the position of the rearview mirror orseat. Thus, the user may push a button or press a switch, which maycause wireless command signals to be sent to the wireless communicationmodule that is associated with the motor or heating element.

In another operation, in response to the wireless signals, the wirelesscommunication module may control operation of the heating element ormotor. That is, the wireless communication module may apply power to, orremove power from, the heating element or motor to thereby apply orremove heat, or adjust a position of the motor. The wirelesscommunication module may receive signals from the Hall sensor of themotor such that a microcontroller of the wireless communication modulemay determine a current position of the motor.

In another operation, an electrical conductor, such as a power cable,may be used to interconnect each of the electrical assemblies and carryelectrical power to each of the electrical assemblies.

The present invention provides a method for effectively controllingseveral actuators wirelessly, thereby implementing the desired function.Novel features of the present invention may include the Ack-dataprotocol with the packet format involving selection and direction bits;wireless control of actuators in automotive and industrial environments;Greedy approximation algorithms for distributing sub-networks on variouschannels; packet formats with selection and direction bits; mutuallyexclusive priority lists maintained by the commanding node; an IDtranslation table including memory positions; function-dependent nodedistribution to sub-networks (a node can be a part of severalsub-networks); and distributed retransmissions for data-Ack protocol.

The invention has been described herein as being applicable to bodydomain systems within automobiles, buses, trucks, etc. However, in otherembodiments, the invention is applicable to other domains within avehicle, such as power train and chassis control, for example.

While this invention has been described as having an exemplary design,the present invention may be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the invention using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as come within known or customarypractice in the art to which this invention pertains.

1. A wireless transmission method, the method comprising the steps of:providing a commanding node and a plurality of sub-networks, each of thesub-networks including at least one responding node; assigning timeslots to the sub-networks such that time slots assigned to each saidsub-network are interleaved in time with time slots assigned to at leastone other said sub-network; and within each said time slot, transmittingat least one acknowledgement packet from the at least one respondingnode before a command packet is sent from the commanding node within thetime slot, each said at least one acknowledgement packet indicating:whether a most recent command packet from the commanding node wascorrectly received by the responding node; and a status of an action bythe responding node in response to the most recent command packet fromthe commanding node.
 2. The method of claim 1 wherein the command packetindicates one of: that the packet is a non-memory packet; and that thepacket is a memory packet.
 3. The method of claim 1 wherein the statusof the action by the responding node comprises one of: that the actionis complete; and that the action is incomplete.
 4. The method of claim 1wherein the command packet indicates a number of the responding nodes inthe sub-network that is assigned to a current said time slot.
 5. Themethod of claim 1 wherein the command packet includes a respectiveselection bit for each of the responding nodes in the sub-network thatis assigned to a current said time slot, each said selection bitindicating whether the respective responding node is to operate.
 6. Themethod of claim 5 wherein a highest priority said responding node thathas its selection bit “ON” transmits a corresponding said acknowledgmentpacket before any other said responding node in the sub-network.
 7. Themethod of claim 1 wherein the command packet includes at least onedirection bit, each said direction bit corresponding to a respectivesaid responding node in the sub-network that is assigned to a currentsaid time slot, each said direction bit indicating a mode of operationof the respective said responding node.
 8. The method of claim 7wherein, if the respective said responding node includes a motor, thedirection bit indicates a direction of rotation of the motor.
 9. Awireless transmission method, the method comprising the steps of:providing a commanding node and a plurality of sub-networks, each of thesub-networks including at least one responding node; assigning timeslots to the sub-networks such that time slots assigned to each saidsub-network are interleaved in time with time slots assigned to at leastone other said sub-network; and within each said time slot, transmittinga command packet from the commanding node and at least oneacknowledgement packet from the at least one responding node, thecommand packet including: a respective selection bit for each of theresponding nodes in the sub-network that is assigned to a current saidtime slot, each said selection bit indicating whether the respectiveresponding node is to operate; and at least one direction bit, each saiddirection bit corresponding to a respective said responding node in thesub-network that is assigned to a current said time slot, each saiddirection bit indicating a mode of operation of the respective saidresponding node.
 10. The method of claim 9 wherein, if the respectivesaid responding node includes a motor, the direction bit indicates adirection of rotation of the motor.
 11. The method of claim 9 whereineach said at least one acknowledgement packet indicates: whether a mostrecent command packet from the commanding node was correctly received bythe responding node; and a status of an action by the responding node inresponse to the most recent command packet from the commanding node. 12.The method of claim 11 wherein the status of the action by theresponding node comprises one of: that the action is complete; and thatthe action is incomplete.
 13. The method of claim 9 wherein the commandpacket indicates one of: that the packet is a non-memory packet; andthat the packet is a memory packet.
 14. The method of claim 9 wherein ahighest priority said responding node that has its selection bit “ON”transmits a corresponding said acknowledgment packet before any othersaid responding node in the sub-network.
 15. The method of claim 9wherein the command packet precedes the at least one acknowledgementpacket within each said time slot.
 16. A wireless transmission method,the method comprising the steps of: providing a commanding node and aplurality of sub-networks, each of the sub-networks including at leastone responding node; assigning one of a plurality of priority levels toeach of the sub-networks; assigning time slots to the sub-networks suchthat time slots assigned to at least one said sub-network areinterleaved in time with time slots assigned to at least one other saidsub-network of a same said priority level; and within each said timeslot, transmitting a command packet from the commanding node and atleast one acknowledgement packet from the at least one responding node,the command packet including a respective selection bit for each of theresponding nodes in the sub-network that is assigned to a current saidtime slot and is of the same said priority level, each said selectionbit indicating whether the respective responding node is to operate. 17.The method of claim 16 wherein the command packet includes at least onedirection bit, each said direction bit corresponding to a respectivesaid responding node in the sub-network that is assigned to a currentsaid time slot and is of the same said priority level, each saiddirection bit indicating a mode of operation of the respective saidresponding node.
 18. The method of claim 16 wherein said respondingnodes of a same said priority level complete operation before thecommand packets are sent to said responding nodes of lower said prioritylevels.
 19. The method of claim 16 where the commanding node maintainsmutually exclusive responding node priority lists.
 20. The method ofclaim 19 where each said command packet identifies one of the prioritylists to which the command packet is addressed.